Файл: BASIC_SURGICAL_TECHNIQUES budapest.pdf

The circular needel has 3 main groups: taper-point, taper-cutting, and blunt taper. The term ”circular needel” classically refers to ”taper-point circular needel”. Both the tip and the body of the needel are circular. Such this needle seperate the tissue fibers without cutting them up. The taper-point circular needels are generally used in easily penetrable tissues (e.g. peritoneum, abdominal organs, myocardium, and subcutaneous tissues)(Figure 41. A).

At the tip of the taper-cutting needel there are three cutting egdes. These edges gradually become flattened and are finally oblitrated at the body.These needels are developed to sew the sclerotic, scarry, and calssified tissues (e.g. scarry fascia, connective tissue, periosteum, tendon, and calssified vessels). The diameter of the cutting and the penetration caused by cutting edge are smaller than the diameter of the thickest part of the needle (and that of the inserted thread as well). In this way, even after pulling of the thread through the tissue there will not appear any dispropotionality between the stitch channel and the thread. The thread will compeletly fill the stitch channel and -in relation to the luminal structuresthis prevent the body secretions, blood, and infected materials to enter from one space to the other one (Figure 41. B).

The blunt taper needels have a circular body and a blunt tip. This needel serves for: preventing the danger of the needelstick injury (especially important in patients infected with HIV or hepatitis virus) and making possibilty to do suturing in a chronically ill patient with a less chance for needlestick injury of the surgeon or assistants, suturing those solid organs which have blood and lymph vessels, or bile and urinary ducts. While passing through the tissues, a blunttaper needle pushes the delicate structures aside and does not cause a separation in their continuity. It merely produces a slit in the soft connective tissues and solid organs (Figure 41. C).

A B C

Figure 41. Circular needles

A. Taper-point, B. Taper-cutting, C. Blunttaper

Most cutting needles have 3 cutting egdes. The cutting edges are made somehow that they lead to a minimal tissue injury while the needle is passing through the tissue. These needles are suitable for sewing the tough structures (e.g. skin and scarry connective tissues). There are 3 basic types of it: conventional cutting, reversed cutting, and spatula-shaped cutting needles.

In the conventional cutting needle the third cutting edge is facing the internal part of the curved body. In cross-section, we get an imaginary triangle which apex is the middle point of the needle. In the tissue this apex is locating towards the edge of the wound and due to this the suture material, which is located at the edge and is pulled strongly, can lead to tearing of the tissue. In the case of the soft tissues the slamming of the suture material can happen (Figure 42. A). In such cases we use the reversed cutting needle which third cutting edge is facing the external part of the curved body. In cross-section, the base of the triangle is facing the internal part of the curved

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body. In the tissues, this is locating towards the edge of the wound while the apex is facing away from it. In this way, the suture material will be located in penetrating channels of the needle which are acually parallel with the wound edges and this eliminate the ”cutting through tissue” effect of the knotted sutures (Figure 42. B). The spatula-shaped needle is used in ophtalmology to perform the atraumatic penetration between the different layers (Figure 42. C).

Figure 42. Cutting needles

A. Conventional cutting needle, B. Reverse cutting needle, C. Spatula-shaped cutting needle

The body of the surgical needles can be of various shapes, which specifies their use. We have straight (tendon suturing), ski-shaped (laparoscopic suturing), and curved needles. Based on their curvature, 1/4 circle, 1/2 circle, 3/8 circle, 5/8 circle, and combined-curved needles are discerned. This latter one has a parabolically curved body and is bended along another axis as well (Figure 43.).

Figure 43. Shape of the needle

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4.2.2. Suture materials

They are used to unify the incised tissues and to ligate the vessels. In the past, they used many materials as suture materials. Examples include: plant fibers (flax, hemp, cotton, bark), animal tissues (kangaroo’s tendon, sheep intestine), metal fibers (silver, gold), and sterilized human hair. Sir Moynihan, the president of the British Royal College of Surgeons has already addressed the criteria for an ideal suture material in 1912. According to his opinion, they are as follows: suitable for any surgical intervention, easy handling, high tensile strength, knot scurity, monofilamentous structure, causing minimal tissue reaction, having a definable absorbancy time, easy to resterilize, and cheap. Naturally, there is no suture material which can fit all these criteria. There is no ideal suture material but nowdays there are some suture materials which fit many of the above-mentioned criteria. The suture material is chosen based on the physical and biological properties of it, rhythm of the wound healing process, and the factros which are present in the patient (e.g.obesity, infections). The most important properties of the suture materials are as follows: 1. physical properties: caliber, tensile strength, elasticity, capillarity, structure, water absorbent capacity, sterilizability 2. application properties: flexibility, capability to slip in tissue, knotting properties, knot security 3. biological properties: absorbent capacity.

Threads are classified according to the origin of the material (natural or synthetic), the structure (monoor multifilament), and absorbability (absorbable or nonabsorbable).

Natural and synthetic threads

The suture materials are made of natural or synthetic materials. Nowdays (and in many aspects of the life), we are experiencing the renaissance of using the natural substances. Concerning the surgical threads, however, it does not seem to be the same. Table 1 summerizes the advantages and disadvantages of these two types of thread. The main disadvantage of the natural substances is that they contain natural proteins (plant or animal origin). It is well-known that the elimination of the foreign proteins is the basic defensive function of the body. The absorption of these natural substances is done by the enzymatic way. It means that the proteolytic enzymes released from macrophages, neutrophils, and phagocytes will digest these substances. This process leads to a strong inflammatory cellular activity as well.

Most synthetic suture materials are inert and cause only small reactions in the living tissues. Their absroption is done by hydrolysis. It means that there is no need for the cellular elements and proteolytic enzymes. The molecules of these materials are simply disintegrating while H2O is released. In this way, they cause less tissue reaction than natural materials.

Table 1.Comparison of natural and synthetic suture materials

The degree of tissue reaction depends on the substance of the the thread. Example: chromic catgut and catgut are very strong, linen, silk, and polyamide are average, Teflon and polyester are moderate, polypropylene, polyglycolic acid, polydioxanone, steel and tantalium are minimal. Suture materials made of natural substances are still used but in surgery of the 21st century the use of the synthetic suture materials is considered to be modern.

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Monoand multifilament suture materials

Based on the structure, we have monofilament threads (having only one filament or fiber) and multifilament or braided threads (having more than one filament)(Figure 44. A and C). Table 2 summerizes their advantages and disadvantages.

Monofilaments have smooth surfaces and so can pass easier through the tissue causing fewer traumas. They do not lead to serrating (or sawing) phenomenon either. Due to rasping effect of the thread there exists a space between the thread and tissue cells. The bigger this space is, the more extensive the inflammatory (and later on fibrotic and possibly infectious) response is. Bacteria, viruses, and fungal spores can get engaged into the fibers (filaments) of a multifilamentous thread and so can easily be taken from one place to the other. The tumor cells can also adhere to the fibers of a braided thread. Happening so, this kind of thread can easily spread the cancerous cells to the healthy area. In addition to these, the braided threads -based on the capillary principal and differences in the osmolaritiescan cause the tissue secretions, and electrolytes (and together with these microorganisms, and cellular elements) to go from one space to the other one (Figure 44. D).

Figure 44. Schematic picture of a Monofilament thread (A), Thread memory (B), Multifilament thread (C), Magnified picture of a multifilament thread inside the tissue (D)

Table 2. Comparsion of monoand multifilament threads

The multifilament threads are generally used when the knot security and tensile strength are of great importance. Examples inculde: ligation, transfixation, placing the prothesis, joint fascia, and prosthetic valves. In minimal invasive interventions, plastic surgeries, suturing of delicate and fine structures, unifing the hollow organs and tissues for avoiding the transport of bacteria and the capillarity, as well as in oncological surgeries we prefer to use the monofilament thraeds. Many multifilament threads are coated. This let them preserve the characteristics of the

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monofilament threads at least externally but at the same time we can get their advantages of being braided. Manufacturing of monofilaments with better and better mechanical properties lead to improvement of handling and knotting difficulties of these threads.

Absorbable and non-absorbable sutures

Some of the suture materials are sooner or later disappearing and we find no sign of them in the body. These are called the absorbable suture materials. However, the others will stay in their place of insertion –without or with some changesforever. These latter threads are called the non-absorbable ones. Their comparsion is shown in Table 3.

The suture materials are actually needed till that time when the scar tissue is formed which then can replace the function of the threads. In ideal cases the thread is immediately absorbed with a minimal tissue reaction. It is aimful to choose the suture material based on the wound healing properties and dynamics of the given tissue or organ. Doing so, we can select a suture material which keeps its tensile strength for the whole period of time needed. A question arises here: is the tissue reaction developing during the absroption of an absorbable suture material or the foreign body reaction which occurs due to a nonabsorbable suture material more harmful to the patient?

Two types of absorption are: enzymatic and hydrolysis. The enzymatic absorption is active and done by celluar elements. It is the characteristic of the natural suture materials which contain proteins. The results of it can be severe tissue reaction, activation of the inflammatrory processes, formation of the microabsceses, and pathologic scar tissue. Its duration of absorption can not be defined and in different structures significantly different results can be obtained from the same suture material.

The hydrolysis is passive and done without participation of the celluar elements. It is the characteristic of the synthetic suture material. During hydrolysis the chemical and physical bonds located between the molecules of the suture material, become loose and the thread is disintegrated to such substances which are similar to the natural metabolites of the body and are lost from the body. The duration of the absorption of these suture materials can be estimated.

The advantages of the non-absorbable suture materials can be important when due to the properties of the tissue even after a long time there is no possibilty for formation of a scar which can insure a real mechanical strength. Exampels for this include: implantation of the cardiac prosthetic valves, implantation of the protheses which replace the ligaments of the joint, and fixation of the vascular grafts. It is important to know that always there is a possibilty for development of a severe fibrotic reaction around even the most modern and inert suture materials. This can be a bed for granulomas, microabscesses and rejection of the sutures.

Taken together, we can say that with some exceptions the synthetic, absorbable suture materials -which are absorbed by hydrolysis-, are prefered.

Table 3.Comparsion of absorbable and non-absorbable suture materials

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